Sonoma State University biology professor Brent Hughes and his colleagues published an article February 1, 2024 in the highly respected, peer-reviewed journal Nature. They note that some biophysical features that make Elkhorn Slough, an estuary in the middle of Monterey Bay, a resilient coastal ecosystem are improving, likely because of the sea otters feeding on plant-eating marsh crabs.
“When thinking about reintroducing sea otters outside their current range, salt marshes could be a very effective and affordable new tool for our conservation toolkit, benefitting both the sea otter and salt marsh,” lead author Brent Hughes said of the study conducted over the course of a decade at Elkhorn Slough.
Experiments combined with observations collected on the ground and by aerial photography confirmed that at sites with large populations of sea otters, erosion of salt marshes had slowed to a halt by the study’s end. Some marshes were even expanding.
Elkhorn Slough, like many other West Coast estuaries, was once an important foraging and nursery habitat for sea otters. To stay warm in frigid Pacific Ocean waters, adult otters need to eat the equivalent of about 25% of their body weight every day, or around 20 to 25 pounds of food. Crabs are one of their favorite meals. But after fur traders hunted the local otter population nearly to extinction, Elkhorn Slough’s crabs were left without sea otter predators for over a century, allowing their populations to explode.
“Crabs eat salt marsh roots, dig into salt marsh soil, and over time can cause a salt marsh to erode and collapse. This had been happening at Elkhorn Slough for decades until otters were reintroduced in the mid-1980s,” Hughes said. “Our results show that recovery of top predators can add stability to a collapsing ecosystem. Salt marsh ecosystems like this are critical to fisheries, biodiversity, carbon sequestration, and shoreline protection.”
Funding came from the the David H. Smith Research Conservation Fellowship and the Cedar Foundation to Hughes and Silliman; National Science Foundation CAREER grants to Silliman and Angelini; and from the Rebecca and Steve Sooy Fellowship in Marine Mammals to Hughes and Beheshti, the Stolarz Foundation (Silliman), and the Lenfest Ocean Program (Silliman).
This article was modified from: https://news.sonoma.edu/article/%E2%80%9Csignificant-otters%E2%80%9D-nature-cover-article-features-ssu-professor-brent-hughes%E2%80%99-research